Method of minimizing the octane demand of an engine



METHOD OF MINIMIZIN G THE OCTANE DEMAND OF AN ENGINE John D. Bartleson,

to The Standard poration of Ohio N Drawing. Application January 21, 1953, Serial No. 332,567

5 Claims. (Cl. 44-76) Beachwood Village, Ohio, assignor Oil Company, Cleveland, Ohio, a cor- The present invention relates to a method of minimizing the tendency of an internal combustion engine to knock and to a liquid motor fuel useful in said method.

It is well known that deposits quickly accumulate in the combustion chambers of internal combustion engines such as those used in automobiles. A spark-ignition type engine containing deposits is said to have a higher octane requirement than a clean engine because it requires a gasoline with a higher octane rating if the engine is not to knock. This becomes apparent to the driver of an automobile having a dirty engine by the tendency of the engine to knock while accelerating, climbing a hill or otherwise operating the engine under greater than normal load. The deleterious effects of such accumulations of deposits is particularly noticeable in engines having a high compression ratio because the margin between the octane numbers of gasolines on the market and the octane requirement of the engine when clean is narrower than for engines having lower compression ratios. When such an engine becomes dirty the octane number of the gasoline required by the engine in order not to knock is increased and often reaches a value higher than the octane rating of gasolines generally available.

When the fuel used in an internal combustion engine contains an agent which in effect raises the octane rating of the fuel, such as tetraethyl lead, in concentrations of about 0.5 to 6.0 cc. per gallon, normally about 3.0 cc. per gallon, the increase in octane requirement of the engine with continued use becomes greater than when non-leaded fuels are used, especially under mild conditions simulating ordinary driving. Thus, whereas the octane requirement of an internal combustion engine operating on non-leaded fuel may increase from say 70 for a clean engine to 78 for a dirty engine and then level 01f at that figure, the octane requirement in the same engine, if run on leaded fuel, will increase to 85 or more for a dirty engine before levelling off.

It is well known, of course, that ordinarily the octane requirement of an engine, whether it be an automobile, marine or airplane engine, is reduced in order to restore or at least to approach its original efficiency by the process of removing a cylinder head and grinding or abrading off the deposits found on the various surfaces of the combustion chamber, such as the piston top, the cylinder head and the intake and exhaust valves. This method, while quite effective, has the disadvantage of requiring skilled labor and a considerable amount of time to dismantle, clean and reassemble the engine. It therefore has the very important additional disadvantage of making it necessary to withdraw the vehicle completely from service while the engine is being overhauled.

A great number of other methods have been proposed heretofore for cleaning the combustion chambers of an engine without removing the cylinder head. One of these methods is that of introducing a liquid solvent into the carburetor while the engine is running. Although this method produces impressive billows of smoke at the exhaust, it has been found, upon taking apart an engine so treated, that little of the deposits are actually removed.

It has now been found that it is possible to minimize the octane requirement of an internal combustion engine, i. e., reduce the octane requirement of a dirty engine or suppress the octane requirement increase of a clean engine, by introducing into the combustion chambers thereof, while operating the engine with a liquid motor fuel, a complex reaction product of the types and Its Derivatives, chapter 4, pages 61-74, i. e., a reaction product of boron trifluoride with an organic:

described in Boron Trifluorides Booth and Martin (1949),

oxygen compound.

The introduction of the organic boron trifluoride reac-- tion product into the combustion chambers of the engine:

while it is running may be effected in a number of ways, e. g., by pouring the material into the carburetor, injec-- tion into the intake manifold through an auxiliary fuell injection device or from a dispenser, such as is describedl in U. S. Patent 2,622,767 of Kovalik and Witter, or by adding a fuel-soluble form thereof to the motor fuel in: the tank.

The organic oxygen compound reacted with boron tri-- fluoride in order to prepare the complex reaction product may be an alcohol, an ether, or a carbonyl such: as an aldehyde, a ketone, an acid, an acid anhydride, an ester or a mixed compound containing a carbonyl. group. Boron trifluoride etherates, particularly combi-- nations of boron trifluoride with methyl and ethyl ethers,,- such as:

' BF3.O(CH3)2Methyl etherate BF .20 CH3 2Methyl dietherate BF 3.0 CzHs) 2Ethyl etherate BF3.2O C2H5) 2Ethyl dietherate are preferred.

Other boron trifluoride etherates typical of those that are useful for the purposes of this invention include;

BF3.O(CH3) (C2H5)Methylethyl etherate BF3.O(CH3) (C5H11)Methylamyl etherate BF3.0(CH2CH2CH3 )z-Normal propyl etherate BFs.2O(CH2CH2CH3)2Norma1 dipropyl etherate BF3.O[ CH3 2CH2] 2Isopropyl etherate BF3.O (CH3)2CH2] (CHs)Isopropyl methyl etherate: BF3.O(CH2CH2CH2CH3)2Normal butyl etherate In the preferred form of the invention, particularly when the compound is added to the motor fuel in the: tank, the boron trifluoride compound is dissolved in an: organic solvent, such as for example methyl-, ethyl-,. propyl-, butyland amyl alcohol, which in turn is sol-- uble in the fuel. Isopropyl alcohol is preferred from: the standpoint of vent is merely a carrier for the complex boron compound; and is believed to take no part in reducing the octane: demand of a dirty engine other than to maintain the boron compound uniformly distributed in the'motor fuel..

In the embodiment of the invention wherein the boron trifluoride compound is dissolved in a suitable solvent: and the resulting solution is blended with the motor fuel as an additive, the concentration of the boron trifluoride compound in the solvent is not critical and may' vary within wide limits, depending in the final analysis: upon the solubility the amount of additive blended with the motor fuel. Thus, for example, concentrations as low as 5% and. as high as 50% have been found to be effective.

The amount of additive blended with the motor fuel. is likewise not critical and may also vary within wide limits. It has been found generally that proportions in. excess of about 5% do not result in appreciably greater desirable effects and that proportions as low as 0.02%

Patented June 19, 1956' economics and solubility. The sol- V of the compound in the solvent and.

and lower are effective. It is preferable to blend the motor fuel with a minor proportion of the boroncontaining additive, e. g., of the order of between 0.02 and by weight.

The essential factor in determining the concentration of the boron trifluoride compound in the solvent and the amount of additive blended with the motor fuel is the final concentration of the boron trifiuoride compound in the fuel. I have found that concentrations ranging from about 0.01% to about 2.5% are efiective in reducing the octane demand of a dirty engine and in suppressing the octane demand increase of a clean engine.

The motor fuel with which the additive is blended may be a leaded or unleaded gasoline.

The primary advantage of the present invention is that it provides an extremely simple method of treating an internal combustion engine to obtain an appreciable reduction in the octane demand of the engine with the ultimate result of making it possible to operate the engine without knocking on a fuel of lower octane rating than was previously possible.

This and other advantages, as well as. the utility of the invention, will become further apparent from the following example, it being understood, however, that this example is not to be considered as limitative in scope.

Example 1 A standard Chevrolet passenger car engine was run until the octane demand of the engine reached an equilibium octane requirement rating of 85. The engine was then run for one hour at full load, simulating load operation at approximately 65 M. P. H. Within the first several minutes of this run one pint of a 5% by volume solution of BFz.0(CzI-l5)2 dissolved in methanol was poured into the carburetor at a rate low enough to avoid stalling the engine. At the end of the run the engine was tested for octane requirement and was found to have an octane requirement of 84. The engine was then operated for 1 /2 hours at part load, simulating load operation at M. P. H., during which a second pint of the same solution was utilized in the same manner as before. At the end of this run it was found that the octane requirement of the engine had been reduced to 82. Finally, the engine was run for an additional 2 /2 hours at part load, in the course of which one pint of a by volume solution of BF3.O(C2H5)2 in methanol was added as before. At the end of this run the octane requirement of the engine was found to have been reduced to 79.

This test demonstrates the ability of the additive of the present invention to reduce the octane requirement of a dirty engine from 85 to 79 while operating the engine.

Example 2 tinuously throughout the test into the intake manifoldat such a rate that the concentration of the additive was 4% by volume of the fuel charge. Test conditions were as follows:

Octane number of fuel 82 Crankcase oil SAE 30 Barometric pressure 29.25 Engine speed, R. P. M 600 Before introduction of the BFs-etherate additive, a reference fuel of 79 octane numbers gave. a knock intensity rating of 59 on the knockmeter. After the engine had been run on fuel containing the BFs-etherate, the same knock intensity rating was obtained with a 76 octane numbers fuel, indicating that the octane demand of the engine had been reduced by three numbers.

This test, as well as that of Example. 1, demonstates the ability of the boron trifiuoride compounds, when introduced into the combustion chambers by any suitable means, e. g., with the fuel or separately, to effect a significant reduction in the octane requirement of anengine.

It is to be understood that various substitutions and modifications will readilyoccur to those skilled in the art upon reading this description. Such substitutions and modifications are intended to be included within the scope of the invention as defined in the appended claims.

I claim:

1. A gasoline containing from about 0.02 to about 5% by Weight of an additive comprising a complex reaction product of boron trifluoride with an organic oxygen compound selected. from the group consisting of alcohols, ethers and carbonyls and a gasoline-soluble solvent for said reaction product.

2 A gasoline containing a minor proportion of an additive comprising from about 0.01 to about 2.5% by weight, based on the weight of the fuel, of acomplex reaction product ofboron trifiuoride with an organic oxygen compound selected from the group consisting of alcohols, ethers and carbonyls and a gasoline-soluble solvent for said reaction product.

3. A gasoline containing a minor proportion of an additive comprising from about 0.01 to 2.5% by weight, based on the weight of the gasoline, of a complex reaction product of boron trifluoride with an organic oxygen compound selected from the group consisting of alcohols, ethers and carbonyls and an alcohol solvent for said reaction product.

4. A gasoline containing from about 0.02 to about 5% by weight of an additive comprising a boron t-rifiuoride etherate dissolved in an alcohol.

5. Gasoline containing from about 0.02 to about 5% by weight of an. additive comprising a boron trifiuoride lower alkyl etherate dissolved in a lower alkyl-monohydric alcohol.

References Cited in the. file of this. patent UNITED STATES PATENTS 1,501,568 Midgley July 15, 1924 2,151,432 Lyons et a1 Mar. 21, 1939 2,558,358 Carlson et al Mar. 11, 1952 2,611,745 Kipp Sept. 23, 1952, 2,622,767 Kovalik Dec. 23, 1952 OTHER REFERENCES Motor Fuel Preparation and Application," Nash. and Howes, vol. 2. Pub. by Wiley & Sons, New York, 1935, pp. 341-346.

Industrial and Engineering Chemistry, vol. 43, No. 12, December 1951, pp. 284-1-43-44-76. 

1. A GASOLINE CONTAINING FROM ABOUT 0.02 TO ABOUT 5% BY WEIGHT OF AN ADDITIVE COMPRISING A COMPLEX REACTION PRODUCT OF BORON TRIFLUORIDE WITH AN ORGANIC OXYGEN COMPOUND SELECTED FROM THE GROUP CONSISTING OF ALCOHOLS, ETHERS AND CARBONYLS AND A GASOLINE-SOLUBLE SOLVENT FOR SAID REACTION PRODUCT. 